The ornamental design for a supportassembly, as shown and described.
FIG. 1 is a perspective view of a support assembly showing our new design, the support assembly including a support foot and fully installed connectors;
FIG. 2 is a top plan view thereof; and
FIG. 3 is a bottom plan view thereof;
FIG. 4 is a front elevation view thereof;
FIG. 5 is a rear elevation view thereof;
FIG. 6 is a side elevation view thereof;
FIG. 7 is the other side elevation view thereof; and,
FIG. 8 illustrates a rail element connected to the support assembly of FIG. 1, wherein the broken lines depict the rail element that forms no part of the claimed design.